When a picture is projected on a projection surface using an image projector such as a projector device, the picture may be corrected in accordance with the texture of the projection surface and the change of the projection surface. By such a technique, a good picture is projected on any projection surface. Typically, in such a technique, when the picture is corrected in accordance with the change of the projection surface, information regarding the projection surface such as reflectance needs to be estimated by comparing the projection image projected on the projection surface with the capture image obtained by capturing the projection image. Here, the projection image and the capture image need to be associated with each other in one-to-one correspondence in order to accurately estimate the information regarding the projection surface.
However, when a moving image is displayed, for instance, the projection image may be changed during acquiring the capture image. Then, accurate information regarding the projection surface cannot be estimated. A technique is desired that can accurately estimate information regarding the projection surface and project a good picture adapted to the projection surface even if the projection image is changed during acquiring the capture image.